Chain Hardness and Grade for Security, Transport and Overhead Lifting

8th Sep 2020

Chain Hardness and Grade for Security, Transport and Overhead Lifting

We frequently get asked about the chain hardness of our overhead lifting chain. 

Our security chain is Grade 100 lifting chain designed to make slings for overhead lifting - and is not manufactured or proof-tested in the same manner as purpose-manufactured "security chain," intended solely for security applications. 

Defender Security Lock with keys and 4' chain

G100 chains are not heat treated to a specific hardness range like security chain, but instead to tensile requirements of the chain being heat treated. G100 chain is tempered after the hardening process to increase the ductility of the chain. Ductility is a measure of a material's ability to undergo significant plastic deformation before rupture or breaking, which may be expressed as percent elongation or percent area reduction from a tensile test. 

Hardness values on G100 Overhead Lifting chain are generally not published by chain manufacturers. Our chain supplier has done limited hardness testing of their G100 chain and it ranges from 39 to 50 Hrc. 

Security chain is normally through hardened and water quenched. This gives the chain a Rockwell hardness between 45-48 Hrc, for comparison - so, very comparable in range to the hardness that Grade 100 Lifting Chain generally produces, within a more narrow range. 

In addition, our security chain is protected by industrial grade sling protector sleeves designed to prevent damage and wear, adding an additional level of difficulty to anyone attempting to cut the chain it protects. 

We feel that our security chain offers the best balance of cost, security, and weight for typical security needs where you want more security than the typical consumed security solutions you find at a bicycle shop or the sporting goods department of your local Superstore. Professional crane operators and their crews depend on this chain to suspend very heavy loads over their heads every day - and the tensile strength which makes the chain able to stretch before breaking also makes it difficult to cut. We use hydraulic devices to cut our chain to size, and the cutting bits must be replaced frequently. Cutting our lifting chain chips and dulls edges. 

A determined thief can cut any chain, with the right equipment - but they will probably damage or ruin their cutting device on our chain, if they are successful. It makes our security chain an excellent choice for security application where you need something better than the average off-the-shelf solution. 

Popular Mechanics has an interesting article on Bolt Cutter-Proof chain for additional reading. 

More detail on chain Grade is available at this link.